1. Field of the Invention
This invention relates to a process and an apparatus whereby color images, particularly computer generated images for such items as air traffic control displays, binocular microscopy, and viewing of printed pictures, may be generated, viewed and perceived as having depth.
2. Description of the Prior Art
Previous processes for viewing stereoscopically formed images require the generation of at least two images of the same scene. This usually took the form of a right side view and a left side view and required the use of a separate system to separate the images by feeding one of the images to each eye. Thus there were formed two laterally displaced essentially simultaneously exposed negatives or impressions in order to form two images of the scene. The lateral displacement between the two images was usually such that it was equivalent to the distance between the viewer's eyes. The results were viewed through a stereo opticon which allowed each eye to see only one of the images portrayed by the negative or the impression. The difference between the two images seen by the viewer was translated by the brain into a sense of depth to give the impression of a three-dimensional scene. This technique was mainly applicable to black and white images.
For purposes of colored images the separation required was usually effected by producing a first image along one line of sight of the scene which was limited in color content by a filter to one half of the visible line spectrum and producing a second image along another line of sight of the scene which was limited in color content by a filter to the remaining half of the visible color spectrum. The two images were then combined and projected onto a common screen for a movie or printed upon a medium. The result was viewed by placing a different color filter in front of each eye with each filter being essentially exclusive in order to permit each eye to see only one of the color limited scenes. The discrepancy existing in the scenes which were perceived between the viewer's eyes was translated by the brain to provide a sense of depth and hence a three-dimensional effect.
Recent variations including that disclosed in U.S. Pat. No. 4,281,341 provide for a stereoscopic television system which uses a switchable optical polarizer to alternately form images which correspond to the left and right eyes on the television camera tube. A corresponding switchable polarizer was used in combination with the television monitor to produce images which are alternately vertically and horizontally polarized.
One of the primary disadvantages with regard to the prior art methods is the necessity of generating at least two images which represent different perspectives of each scene to be viewed. Full color images were only possible by using polarizing filters over the eyes which required a spinner polarizer to be placed in front of the video display, scanned in synchronization with alternating scenes. Another method was a complicated shutter arrangement whereby the image to each eye is alternately cut off and passed according to which image is on the screen. Each of these systems are both complicated and difficult to synchronize.